The present invention relates to an MTF (modulation transfer function) measuring method and system. More particularly, the present invention relates to a method and system for calculating an MTF by Fourier-transforming an LSF (line spread function).
An MTF stands for a modulation transfer function, and indicates the spatial resolution of an image reconstructed by an X-ray computed tomography (CT) system. The MTF is therefore utilized in order to assess the performance of the X-ray CT system. The MTF is calculated by Fourier-transforming an LSF (line spread function) detected in the reconstructed image (refer to, for example, Non-patent Document 1).
[Non-patent Document 1] “Series of Advancements in Electronic Engineering No. 9 CT Scanner—X-ray Computed Tomography System” written by Yoshinori Iwai (Corona Publishing Co., Ltd., May in 1980, P. 66-P. 68).
In order to calculate an MTF highly precisely, it is essential to detect the center of an LSF accurately. The center of an LSF is detected as a point in an LSF image which exhibits the largest pixel value. Since the detected center position is likely to contain an error because of the influence of noise, there is therefore difficulty in measuring the MTF highly precisely.